The ones who do have a high toss obviously are more susceptible to the wind, but other than that, a lot of serves with high ball tosses just are error-prone in general. Take Sharapova's or Ivanovic.

It begs the question; why don't they just toss lower?

I know they have their own distinct serving style which they're stuck with, but are they stuck with a bad habit? Does having a very high ball toss hold any advantage over tossing the ball just high enough to get your ideal contact point (ie. Dolgopolov, Monfils, Roddick)?

Hitting a low toss at it's peak "requires perfect timing and coordination between the toss and racquet swing. The racquet must move a considerable distance and arrive at a particular point in time and space the exact instant the ball gets there. There is no leeway. On the other hand, a higher toss introduces some slack in the system. The server gains flexibility. He can slow down or speed up the action as the situation requires and contact the ball where he wants on the way down. His trade-off is having to hit a moving ball rather than a stationary one."

I find this to be true although there is a point of diminishing return if you toss too far above your hitting point.

A higher toss gives them more time and decreases the chance of hitting tthe ball not as high as possible. but still I think too high is not good. Throw just to the contact point like goran is dificult too (although much harder to read than a high toss but also requires more timing and can cause rushing) but I think it should not much higher than a foot or so over the contact point.

if you look at the physics, a toss barely above or just at the point of contact would be ideal. when you start tossing it higher than that, the ball is actually traveling faster on the way down, thus giving you less time to hit the ball and making that perfect contact more difficult. thats probably the reason all of the best servers have a lower toss. the ball is suspended at the peak, so it makes solid contact much more consistent since the ball is either not moving or moving very slowly.